This invention relates to a pattern recognition system for detecting the shape and the position of an object, and more particularly to a pattern recognition system which can recognize an object having a complicated shape or not being completely equivalent to a standard pattern.
Automatic assembly apparatus and automatic article suppliers have been developed and installed in factories in order to automatically manufacture products, some of which provide pattern recognition systems. Signals produced from the pattern recognition systems and corresponding to the shape and the position of an object are utilized to control the automatic assembly apparatus and the automatic article suppliers.
Now, in the conventional pattern recognition system, an object to be recognized in an image pattern which is obtained from a picture tube, has been compared with a standard pattern equivalent to the object in shape, so that a presence and a position of the object in the image pattern has been detected in a fact that the partial pattern of the image pattern is placed in registration with the standard pattern. It has been, however, necessary that this pattern recognition system has a mask, which will be explained hereinafter, for enough covering of the standard pattern and a large volume of memory corresponding to the size of the mask in order to store the information of the mask. Further, a case where the shape of the object to be recognized in the image pattern is deformed by some cause has a low degree of similarity between the object and the standard pattern since the standard pattern is formed from one mask, and the pattern recognition system results in errors in the recognition of the object. This is one example, which in a case where the object to be recognized is a circle, the size of the circle picked up as an image is variable due to a distance between the circle as the object and the picture tube and the shape thereof is an ellipse when the picture tube is shifted from the axis of the circle, so that the circle cannot be recognized.